Both citrate and hypophosphite in aqueous solution were degraded by advanced oxidation processes （Fe^2＋/H2O2, UV/Fe^2＋/H2O2, and electrolysis/Fe^2＋/H2O2） in this study. Comparison of these techniques in oxidation...Both citrate and hypophosphite in aqueous solution were degraded by advanced oxidation processes （Fe^2＋/H2O2, UV/Fe^2＋/H2O2, and electrolysis/Fe^2＋/H2O2） in this study. Comparison of these techniques in oxidation efficiency was undertaken. It was found that Fenton process could not completely degrade citrate in the presence of hypophosphite since it caused a series inhibition. Therefore, UV light （photo-Fenton） or electron current （electro-Fenton） was applied to improve the degradation efficiency of the Fenton process. Results showed that both photo-Fenton and electro-Fenton processes could overcome the inhibition of hypophosphite, especially the electro-Fenton.展开更多
The effects of aluminum hypophosphite（AHP） as a synergistic agent on the flame retardancy and thermal degradation behavior of intumescent flame retardant polypropylene composites（PP/IFR） containing ammonium polyph...The effects of aluminum hypophosphite（AHP） as a synergistic agent on the flame retardancy and thermal degradation behavior of intumescent flame retardant polypropylene composites（PP/IFR） containing ammonium polyphosphate（APP） and triazine charring-foaming agent（CFA） were investigated by limiting oxygen index（LOI）, UL-94 measurement, thermogravimetric analysis（TGA）, cone calorimeter test（CONE）, scanning electron microscopy（SEM） and X-ray photoelectron spectroscopy（XPS）. It was found that the combination of IFR with AHP exhibited an evident synergistic effect and enhanced the flame retardant efficiency for PP matrix. The specimens with the thickness of 0.8 mm can pass UL-94 V-0 rating and the LOI value reaches 33.5% based on the total loading of flame retardant of 24 wt%, and the optimum mass fraction of AHP/IFR is 1：6. The TGA data revealed that AHP could change the degradation behavior of IFR and PP/IFR system, enhance the thermal stability of the IFR and PP/IFR systems at high temperatures and promote the char residue formation. The CONE results revealed that IFR/AHP blends can efficiently reduce the combustion parameters of PP, such as heat release rate（HRR）, total heat release（THR）, smoke production rate（SPR） and so on. The morphological structures of char residue demonstrated that AHP is of benefit to the formation of a more compact and homogeneous char layer on the materials surface during burning. The analysis of XPS indicates that AHP may promote the formation of sufficient char on the materials surface and improve the flame retardant properties.展开更多
Aluminum hypophosphite （AP） was used to prepare flame-retarded thermoplastic polyurethane （FR-TPU） composites, and their flame retardancy, thermal degradation and mechanical properties were investigated by limitin...Aluminum hypophosphite （AP） was used to prepare flame-retarded thermoplastic polyurethane （FR-TPU） composites, and their flame retardancy, thermal degradation and mechanical properties were investigated by limiting oxygen index （LOI）, vertical burning test （UL-94）, thermogravimetric analysis （TGA）, cone calorimeter （CC） test, Fourier transform infrared （FTIR） spectroscopy, scanning electron microscopy （SEM） and tensile test. TPU containing 30 wt% of AP could reach a V-0 rating in the UL-94 test, and its LOI value was 30.2. TGA tests revealed that AP enhanced the formation of residual chars at high temperatures, and slightly affected the thermal stability of TPU at high temperatures. The combustion tests indicated that AP affected the burning behavior of TPU. The peak of heat release rate （PHRR）, total heat release （THR） and mass loss rate （MLR） greatly reduced due to the incorporation of AP. The tensile test results showed that both the tensile strength and the elongation at break slightly decreased with the addition of AP. The digital photos and SEM micrographs vitrified that AP facilitated the formation of more compact intumescent char layer. Based on these results mentioned above, the flame-retarding mechanism of AP was discussed. Both the self-charring during the decomposing process of AP and its facilitation to the charring of TPU led to the great improvement in the flame retardancy of TPU.展开更多
Aluminum hypophosphite microspheres(AHP) were synthesized by hydrothermal method using NaH2PO2·H2O and AlCl3·6H2O as raw materials, and then the AHP microspheres were polymerized by surface polymerization of...Aluminum hypophosphite microspheres(AHP) were synthesized by hydrothermal method using NaH2PO2·H2O and AlCl3·6H2O as raw materials, and then the AHP microspheres were polymerized by surface polymerization of micro-nanospheres with cyclic cross-linked poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol)(PZS). A new organic-inorganic poly(phosphonitrile)-modified aluminum hypophosphite microspheres(PZS-AHP) were synthesized by encapsulation and applied to flame retardant thermoplastic polyurethane(TPU). The microstructure and chemical composition of the PZS-AHP microsphere were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray spectroscopy. The thermal stability of PZS-AHP microsphere was explored with thermogravimetric analysis. Thermogravimetric data indicate that the PZS-AHP microspheres have excellent thermal stability. The thermal and flame-retarding properties of the TPU composites were evaluated by thermogravimetric(TG), limited oxygen index tests(LOI), and cone calorimeter test(CCT). The TPU composite achieved vertical burning(UL-94) V-0 grade and LOI value reached 29.2% when 10 wt% PZS-AHP was incorporated. Compared with those of pure TPU, the peak heat release rate(pHRR) and total heat release(THR) of TPU/10%PZS-AHP decreased by 82.2% and 42.5%, respectively. The results of CCT indicated that PZS-AHP microsphere could improve the flame retardancy of TPU composites.展开更多
The electrocatalytic oxidation of hypophosphite on a nickel electrode has been studiedby means of in site UV-Vis subtractive reflectance spectroscopy. An absorbency band around 245um . which was ascribed to the format...The electrocatalytic oxidation of hypophosphite on a nickel electrode has been studiedby means of in site UV-Vis subtractive reflectance spectroscopy. An absorbency band around 245um . which was ascribed to the formation of an intermediate, PHO2-, was observed in theelectrocatalytic oxidation process. Accordingly, the electrocatalytic oxidation of hypophosphitemight undergo a H abstraction of hypophosphite from the P-H bond to form the phosphoruscentred radical PHO2-, which is subsequently electrooxidized to the final product, phosphite.展开更多
Electrochemical behavior of hypophosphite was studied with cyclic voltammogram in acidic solution(pH = 4.6) at 80℃. Two anodic peaks were observed on gold electrode at - 0.44V and - 0.59 V (SCE),respectively, and no ...Electrochemical behavior of hypophosphite was studied with cyclic voltammogram in acidic solution(pH = 4.6) at 80℃. Two anodic peaks were observed on gold electrode at - 0.44V and - 0.59 V (SCE),respectively, and no corresponding cathodic peaks were obtained. The one at - 0.44 V wits ascribed to the oxidation oftautomeric form of hypophosphite, the other at - 0.59 V was due to the oxidation of absorbed form of hypophosphite. The two oxidation reactions were believed to be the electron source of nickel ion reduction in electrolessnickel processes.展开更多
A facile, safe and economical reducing agent, sodium hypophosphite（Na H2PO2·H2O）, has been successfully employed for ambient temperature living radical copolymerization of styrene（St） and methyl methacrylate...A facile, safe and economical reducing agent, sodium hypophosphite（Na H2PO2·H2O）, has been successfully employed for ambient temperature living radical copolymerization of styrene（St） and methyl methacrylate（MMA）. Such effective reducing agent significantly improved the reactivity of low reactive St monomers during the copolymerization, where the reactivity ratios of St and MMA were determined to be 0.50 and 0.36 by Finemann-Ross method. Thus the copolymerizations proceeded fast and showed typical living/controlled features, as evidenced by pseudo first-order kinetics of polymerization, linear increase in molecular weight versus monomer conversion, and low polydispersity index values. Effects of the concentration of reducing agent and the monomer feed ratio on the copolymerization were investigated in detail. Furthermore, gel permeation chromatography and 1H-NMR analyses as well as chain extension experiments confirmed the high chain-end functionality of the resultant copolymer.展开更多
The deactivation of nickel hydroxide to the electrooxidation of hypophosphite on anickel electrode was studied by means of in situ UV-Vis subtractive reflectance spectroscopy. Theexperimental results show that when th...The deactivation of nickel hydroxide to the electrooxidation of hypophosphite on anickel electrode was studied by means of in situ UV-Vis subtractive reflectance spectroscopy. Theexperimental results show that when the potential is lower than-1.0 V (SCE), the surfacc on nickelelectrode is free of nickel hydroxide, on which hypophosphite is active. When the potential movespositively to about-0.75V, two absorbency bands around 300 nm and 550 nm, which were ascribedto the formation of α-nickel hydroxide, were observed, nickel is oxidized to α-nickel hydroxide.Severe deactivation of the surface occurs when the nickel surface is covered with nickel hydroxide,which separates the hypophosphite ion from nickel substrate.展开更多
Kinetic model of hypophosphite oxidation on a nickel electrode was studied in D2O solution in order to reach a better understanding of the oxidation mechanism. In the model;he electrooxidation of hypophosphite undergo...Kinetic model of hypophosphite oxidation on a nickel electrode was studied in D2O solution in order to reach a better understanding of the oxidation mechanism. In the model;he electrooxidation of hypophosphite undergo a H abstraction of hypophosphite from the P-H bond to form the phosphorus-centered radical (PWO2-)-P-., which subsequently is electrochemically reacted with water to form the final product, phosphite. The kinetic equations were derived, and the kinetic parameters were obtained from a comparison of experimental results and the kinetic equations. The process of hypophosphite electrooxidation could be well simulated by this model.展开更多
This paper presents a new method of determining Ge in AuGe alloys by potassium iodate(KIO3)potentiometric titration when Ge(Ⅱ)and Au(0)are simultaneously reduced from Ge(Ⅳ)and Au(Ⅲ)by sodium hypophosphite rather th...This paper presents a new method of determining Ge in AuGe alloys by potassium iodate(KIO3)potentiometric titration when Ge(Ⅱ)and Au(0)are simultaneously reduced from Ge(Ⅳ)and Au(Ⅲ)by sodium hypophosphite rather than by distillation separation.The influences of such conditions as the reduction acidity,the dosage of sodium hypophosphite and the reduction time on the determination of Ge were studied.Ge in AuGe alloys such as AuGe_(12),AuGeNi_(12-2),AuAgGe_(18.8-12.5),and AuAgGeNi_(43.8-6-0.2)was measured with the relative standard deviation(RSD)of 0.10%-0.31%and the recoveries of added standard Ge in sample of 99.40%-100.40%under the conditions of 0.40-0.80 mol·L^(-1)HCl,3.3 mol·L^(-1)H^(3)PO^(4),15 g sodium hypophosphite,and reduction time of40 min.The new method presented is of high accuracy in results,good stability and sensibility in end-point,and easy operation and strong selectivity of determination.展开更多
Cobalt-Boron oxides containing catalyst CoO·B2O3 (CoB2O4) are synthesized for hydrogen generation by catalytic reforming of basic solution of sodium hypophosphite (NaH2PO2) and identified by chemical and X-ray an...Cobalt-Boron oxides containing catalyst CoO·B2O3 (CoB2O4) are synthesized for hydrogen generation by catalytic reforming of basic solution of sodium hypophosphite (NaH2PO2) and identified by chemical and X-ray analysis. Reforming is performed in temperature range of 30°C - 80°C. Reaction rate constants at each value of temperature (k30°C = 8.53 × 10?4 s?1;k40°C = 1.62 × 10?4 s??;k50°C = 3.06 × 10?3 s?1;k60°C = 5.06 × 10?3 s?1;k80°C = 1.39 × 10?2 s?1), temperature coefficient of rate of chemical reaction (γ = 0.917) and activation energy (EA = 49.59 kJ·mol?1) are calculated.展开更多
In this study,we developed a tandem photo-assisted electrochemical(PA-EC)chemical strategy for both energy-saving ammonia/fertilizer synthesis and comprehensive nitrogen-and phosphorus-rich wastewater treatment,in whi...In this study,we developed a tandem photo-assisted electrochemical(PA-EC)chemical strategy for both energy-saving ammonia/fertilizer synthesis and comprehensive nitrogen-and phosphorus-rich wastewater treatment,in which synchronous hypophosphite ion(H_(2)PO_(2)^(-))oxidation to phosphate ion(PO_(4)^(3–))(POR)and nitrate reduction(NO_(3)RR)to ammonia(NH_(3))occur,followed by cascade chemical precipitation to generate struvite.Herein,a bifunctional Cu_(2)O@NiFe_(2)O_(4)Z-scheme heterojunction with a yolk/shell structure and oxygen vacancies(OVs)was designed and developed to optimize the NO_(3)RR/POR.Serving as a key component,the established PA-EC system consisted of a Janus Cu_(2)O@NiFe_(2)O_(4)/NF self-supporting integrated photocathode and a Cu_(2)O@NiFe_(2)O_(4)/NF photocathode with efficient struvite PA-EC synthesis performance under a low cell voltage of 1.6 V vs NHE.Specifically,Janus Cu_(2)O@NiFe_(2)O_(4)/NF photocathode exhibits superior performance with a high NH3 yield of 38.06 mmol L^(-1)and a faradaic efficiency(FE)of 92.31%at 1.6 V vs.NHE and enables ammonia FE over 60%in a broad NO_(3)–concentration window of 0.005–0.5 mol L^(-1).The photoassisted electrochemical catalytic mechanism and reaction pathway for struvite synthesis on Cu_(2)O@NiFe_(2)O_(4)were investigated through a series of experiments and theoretical calculations.The results demonstrated the critical roles of the interfacial electric field,void confinement,and oxygen vacancies in promoting the overall catalytic efficiency.These encouraging results warrant further studies on combined P and N recovery for efficient production of valuable fertilizers.展开更多
基金The authors thank the "National" Science Council, Taiwan, China for financially supporting (No. NSC95- 2211-E-006-032).
文摘Both citrate and hypophosphite in aqueous solution were degraded by advanced oxidation processes （Fe^2＋/H2O2, UV/Fe^2＋/H2O2, and electrolysis/Fe^2＋/H2O2） in this study. Comparison of these techniques in oxidation efficiency was undertaken. It was found that Fenton process could not completely degrade citrate in the presence of hypophosphite since it caused a series inhibition. Therefore, UV light （photo-Fenton） or electron current （electro-Fenton） was applied to improve the degradation efficiency of the Fenton process. Results showed that both photo-Fenton and electro-Fenton processes could overcome the inhibition of hypophosphite, especially the electro-Fenton.
基金financially supported by the Fundamental Research Funds for the Central Universities(DL12CB07)Youth Science Fund of Heilongjiang Province(No.QC2011C102)Heilongjiang Major Research Projects(GA12A102)
文摘The effects of aluminum hypophosphite（AHP） as a synergistic agent on the flame retardancy and thermal degradation behavior of intumescent flame retardant polypropylene composites（PP/IFR） containing ammonium polyphosphate（APP） and triazine charring-foaming agent（CFA） were investigated by limiting oxygen index（LOI）, UL-94 measurement, thermogravimetric analysis（TGA）, cone calorimeter test（CONE）, scanning electron microscopy（SEM） and X-ray photoelectron spectroscopy（XPS）. It was found that the combination of IFR with AHP exhibited an evident synergistic effect and enhanced the flame retardant efficiency for PP matrix. The specimens with the thickness of 0.8 mm can pass UL-94 V-0 rating and the LOI value reaches 33.5% based on the total loading of flame retardant of 24 wt%, and the optimum mass fraction of AHP/IFR is 1：6. The TGA data revealed that AHP could change the degradation behavior of IFR and PP/IFR system, enhance the thermal stability of the IFR and PP/IFR systems at high temperatures and promote the char residue formation. The CONE results revealed that IFR/AHP blends can efficiently reduce the combustion parameters of PP, such as heat release rate（HRR）, total heat release（THR）, smoke production rate（SPR） and so on. The morphological structures of char residue demonstrated that AHP is of benefit to the formation of a more compact and homogeneous char layer on the materials surface during burning. The analysis of XPS indicates that AHP may promote the formation of sufficient char on the materials surface and improve the flame retardant properties.
基金financially supported by the National Natural Science Foundation of China(Nos.50933005 and 51121001)the Program for Changjiang Scholars and Innovative Research Teams in Universities of China(IRT 1026)
文摘Aluminum hypophosphite （AP） was used to prepare flame-retarded thermoplastic polyurethane （FR-TPU） composites, and their flame retardancy, thermal degradation and mechanical properties were investigated by limiting oxygen index （LOI）, vertical burning test （UL-94）, thermogravimetric analysis （TGA）, cone calorimeter （CC） test, Fourier transform infrared （FTIR） spectroscopy, scanning electron microscopy （SEM） and tensile test. TPU containing 30 wt% of AP could reach a V-0 rating in the UL-94 test, and its LOI value was 30.2. TGA tests revealed that AP enhanced the formation of residual chars at high temperatures, and slightly affected the thermal stability of TPU at high temperatures. The combustion tests indicated that AP affected the burning behavior of TPU. The peak of heat release rate （PHRR）, total heat release （THR） and mass loss rate （MLR） greatly reduced due to the incorporation of AP. The tensile test results showed that both the tensile strength and the elongation at break slightly decreased with the addition of AP. The digital photos and SEM micrographs vitrified that AP facilitated the formation of more compact intumescent char layer. Based on these results mentioned above, the flame-retarding mechanism of AP was discussed. Both the self-charring during the decomposing process of AP and its facilitation to the charring of TPU led to the great improvement in the flame retardancy of TPU.
基金Supported by the Opening Project of Hubei Three Gorges Laboratory (No.SK213008)the Innovation Fund of Key Laboratory of Green Chemical Process of Ministry of Education (No.GCXP202109)。
文摘Aluminum hypophosphite microspheres(AHP) were synthesized by hydrothermal method using NaH2PO2·H2O and AlCl3·6H2O as raw materials, and then the AHP microspheres were polymerized by surface polymerization of micro-nanospheres with cyclic cross-linked poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol)(PZS). A new organic-inorganic poly(phosphonitrile)-modified aluminum hypophosphite microspheres(PZS-AHP) were synthesized by encapsulation and applied to flame retardant thermoplastic polyurethane(TPU). The microstructure and chemical composition of the PZS-AHP microsphere were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray spectroscopy. The thermal stability of PZS-AHP microsphere was explored with thermogravimetric analysis. Thermogravimetric data indicate that the PZS-AHP microspheres have excellent thermal stability. The thermal and flame-retarding properties of the TPU composites were evaluated by thermogravimetric(TG), limited oxygen index tests(LOI), and cone calorimeter test(CCT). The TPU composite achieved vertical burning(UL-94) V-0 grade and LOI value reached 29.2% when 10 wt% PZS-AHP was incorporated. Compared with those of pure TPU, the peak heat release rate(pHRR) and total heat release(THR) of TPU/10%PZS-AHP decreased by 82.2% and 42.5%, respectively. The results of CCT indicated that PZS-AHP microsphere could improve the flame retardancy of TPU composites.
文摘The electrocatalytic oxidation of hypophosphite on a nickel electrode has been studiedby means of in site UV-Vis subtractive reflectance spectroscopy. An absorbency band around 245um . which was ascribed to the formation of an intermediate, PHO2-, was observed in theelectrocatalytic oxidation process. Accordingly, the electrocatalytic oxidation of hypophosphitemight undergo a H abstraction of hypophosphite from the P-H bond to form the phosphoruscentred radical PHO2-, which is subsequently electrooxidized to the final product, phosphite.
文摘Electrochemical behavior of hypophosphite was studied with cyclic voltammogram in acidic solution(pH = 4.6) at 80℃. Two anodic peaks were observed on gold electrode at - 0.44V and - 0.59 V (SCE),respectively, and no corresponding cathodic peaks were obtained. The one at - 0.44 V wits ascribed to the oxidation oftautomeric form of hypophosphite, the other at - 0.59 V was due to the oxidation of absorbed form of hypophosphite. The two oxidation reactions were believed to be the electron source of nickel ion reduction in electrolessnickel processes.
基金financially supported by the National Natural Science Foundation of China(No.21074127)
文摘A facile, safe and economical reducing agent, sodium hypophosphite（Na H2PO2·H2O）, has been successfully employed for ambient temperature living radical copolymerization of styrene（St） and methyl methacrylate（MMA）. Such effective reducing agent significantly improved the reactivity of low reactive St monomers during the copolymerization, where the reactivity ratios of St and MMA were determined to be 0.50 and 0.36 by Finemann-Ross method. Thus the copolymerizations proceeded fast and showed typical living/controlled features, as evidenced by pseudo first-order kinetics of polymerization, linear increase in molecular weight versus monomer conversion, and low polydispersity index values. Effects of the concentration of reducing agent and the monomer feed ratio on the copolymerization were investigated in detail. Furthermore, gel permeation chromatography and 1H-NMR analyses as well as chain extension experiments confirmed the high chain-end functionality of the resultant copolymer.
文摘The deactivation of nickel hydroxide to the electrooxidation of hypophosphite on anickel electrode was studied by means of in situ UV-Vis subtractive reflectance spectroscopy. Theexperimental results show that when the potential is lower than-1.0 V (SCE), the surfacc on nickelelectrode is free of nickel hydroxide, on which hypophosphite is active. When the potential movespositively to about-0.75V, two absorbency bands around 300 nm and 550 nm, which were ascribedto the formation of α-nickel hydroxide, were observed, nickel is oxidized to α-nickel hydroxide.Severe deactivation of the surface occurs when the nickel surface is covered with nickel hydroxide,which separates the hypophosphite ion from nickel substrate.
基金The work was supported by the Natural Science Foundation of the Education Commission of Hunan Province(No.99C57)
文摘Kinetic model of hypophosphite oxidation on a nickel electrode was studied in D2O solution in order to reach a better understanding of the oxidation mechanism. In the model;he electrooxidation of hypophosphite undergo a H abstraction of hypophosphite from the P-H bond to form the phosphorus-centered radical (PWO2-)-P-., which subsequently is electrochemically reacted with water to form the final product, phosphite. The kinetic equations were derived, and the kinetic parameters were obtained from a comparison of experimental results and the kinetic equations. The process of hypophosphite electrooxidation could be well simulated by this model.
基金the National High Technology Research and Development Program of China (Nos.2012AA063203 and 2012AA063207)。
文摘This paper presents a new method of determining Ge in AuGe alloys by potassium iodate(KIO3)potentiometric titration when Ge(Ⅱ)and Au(0)are simultaneously reduced from Ge(Ⅳ)and Au(Ⅲ)by sodium hypophosphite rather than by distillation separation.The influences of such conditions as the reduction acidity,the dosage of sodium hypophosphite and the reduction time on the determination of Ge were studied.Ge in AuGe alloys such as AuGe_(12),AuGeNi_(12-2),AuAgGe_(18.8-12.5),and AuAgGeNi_(43.8-6-0.2)was measured with the relative standard deviation(RSD)of 0.10%-0.31%and the recoveries of added standard Ge in sample of 99.40%-100.40%under the conditions of 0.40-0.80 mol·L^(-1)HCl,3.3 mol·L^(-1)H^(3)PO^(4),15 g sodium hypophosphite,and reduction time of40 min.The new method presented is of high accuracy in results,good stability and sensibility in end-point,and easy operation and strong selectivity of determination.
文摘Cobalt-Boron oxides containing catalyst CoO·B2O3 (CoB2O4) are synthesized for hydrogen generation by catalytic reforming of basic solution of sodium hypophosphite (NaH2PO2) and identified by chemical and X-ray analysis. Reforming is performed in temperature range of 30°C - 80°C. Reaction rate constants at each value of temperature (k30°C = 8.53 × 10?4 s?1;k40°C = 1.62 × 10?4 s??;k50°C = 3.06 × 10?3 s?1;k60°C = 5.06 × 10?3 s?1;k80°C = 1.39 × 10?2 s?1), temperature coefficient of rate of chemical reaction (γ = 0.917) and activation energy (EA = 49.59 kJ·mol?1) are calculated.
文摘In this study,we developed a tandem photo-assisted electrochemical(PA-EC)chemical strategy for both energy-saving ammonia/fertilizer synthesis and comprehensive nitrogen-and phosphorus-rich wastewater treatment,in which synchronous hypophosphite ion(H_(2)PO_(2)^(-))oxidation to phosphate ion(PO_(4)^(3–))(POR)and nitrate reduction(NO_(3)RR)to ammonia(NH_(3))occur,followed by cascade chemical precipitation to generate struvite.Herein,a bifunctional Cu_(2)O@NiFe_(2)O_(4)Z-scheme heterojunction with a yolk/shell structure and oxygen vacancies(OVs)was designed and developed to optimize the NO_(3)RR/POR.Serving as a key component,the established PA-EC system consisted of a Janus Cu_(2)O@NiFe_(2)O_(4)/NF self-supporting integrated photocathode and a Cu_(2)O@NiFe_(2)O_(4)/NF photocathode with efficient struvite PA-EC synthesis performance under a low cell voltage of 1.6 V vs NHE.Specifically,Janus Cu_(2)O@NiFe_(2)O_(4)/NF photocathode exhibits superior performance with a high NH3 yield of 38.06 mmol L^(-1)and a faradaic efficiency(FE)of 92.31%at 1.6 V vs.NHE and enables ammonia FE over 60%in a broad NO_(3)–concentration window of 0.005–0.5 mol L^(-1).The photoassisted electrochemical catalytic mechanism and reaction pathway for struvite synthesis on Cu_(2)O@NiFe_(2)O_(4)were investigated through a series of experiments and theoretical calculations.The results demonstrated the critical roles of the interfacial electric field,void confinement,and oxygen vacancies in promoting the overall catalytic efficiency.These encouraging results warrant further studies on combined P and N recovery for efficient production of valuable fertilizers.
